Vehicle having speed control unit

ABSTRACT

A tractor is disclosed as a four-wheel drive vehicle with a movable seat back, with a seat height adjustment and with a varying load capability.

RELATED APPLICATIONS

This application claims priority from U.S. Provisional PatentApplication Ser. No. 61/135,864, filed Jul. 24, 2008, the subject matterof which is incorporated herein by reference.

This application is a divisional of U.S. patent application Ser. No.12/501,944, filed on Jul. 13, 2009, and entitled “VEHICLE HAVING SPEEDCONTROL UNIT,” and is related to U.S. patent application Ser. No.12/501,941, filed on Jul. 13, 2009, and entitled “TRACTOR VEHICLE,” andU.S. patent application Ser. No. 13/859,541, filed on Apr. 9, 2013, andentitled “TRACTOR VEHICLE”, the complete disclosures of which areexpressly incorporated by reference herein.

BACKGROUND OF THE INVENTION

The present disclosure relates to vehicles which may be classified astractors.

Many different types and styles of vehicles are used for utilitypurposes, and many different country laws and regulations apply to manyapplications. Generally, all terrain vehicles (“ATVs”) and utilityvehicles (“UVs”) are used to carry one or two passengers and a smallamount of cargo over a variety of terrains. Most ATVs include an engineincluding between one and three cylinders. Generally, the engine ismounted in the frame of the ATV and most ATVs include a straddle orsaddle type seat positioned above the engine. The seats are typicallyhard mounted to the frame, and do not accommodate multiple ridervariables such as height and weight.

In terms of classification for tractors, each country has a specificrequirement for tractor vehicle classification. Europe has the “CouncilDirective of 25 Jul. 1978 on the approximation of the laws of the memberstates relating to the driver seat on wheeled agricultural or forestrytractors” described in (78/764/EEC) (OJ L 255, 18.9.1978, Pg. 1), thesubject matter of which is incorporated herein by reference.

This Directive requires wheel vehicles to have certain characteristicsin order to achieve classification as tractors. First, the position ofthe backrest must be adjustable (or the seat bottom and the seat backtogether) a minimum distance of 60 mm. A seat must also be adjustable inthe vertical direction by at least 30 mm. The Directive also requiresthat the seat be able to follow a specific load adjustment range ofbetween 385 Newtons (86 pounds) and 923 Newtons (207 pounds) as shown inAppendix II of the above-mentioned Council Directive. Finally, some ofthe directives also require a maximum speed with which the vehicle isdesigned.

It is an object to provide a vehicle of the ATV style, yet comply withthe tractor classification.

SUMMARY OF THE INVENTION

The objects have been accomplished by providing a vehicle, comprising aframe, ground engaging elements, and an engine to motively drive one ormore of the ground engaging elements. A speed control unit controls theengine and a top speed of the vehicle, and comprises an air valvepositioned intermediate the air intake and the engine, a controllerassembly for opening and closing the air valve, where the assemblyincludes a speed sensing mechanism and a controlling unit for openingand closing the air valve.

In another embodiment, a vehicle comprises a frame, ground engagingelements, an engine for motively driving one or more of the groundengaging elements and an air valve positioned intermediate an air intakeand the engine. The air valve is comprised of a valve body having anupper end, and a lower end having an intake side and an exhaust side. Agate valve member is positioned within the valve body and is operated bya guillotine, and the gate valve provides opened and closed positions. Adiaphragm is positioned at the valve body upper end and is operativelyconnected to the guillotine. A first pressure chamber is defined aboveand a second pressure chamber is defined below, the diaphragm. Anaperture extends through the diaphragm connecting the first and secondpressure chambers.

In yet another embodiment, a vehicle comprises a frame, ground engagingelements; an engine for motively driving one or more of the groundengaging elements, and an air valve positioned intermediate an airintake and the engine. The air valve is comprised of a valve body havingan upper end, and a lower end having an intake side and an exhaust side,the intake side comprises a raised and contoured section. A gate valvemember is positioned within the valve body and is operated by aguillotine. The gate valve member provides opened and closed positions,wherein in the closed position, the gate valve member is positionedbehind the raised and contoured section. A diaphragm is positioned atthe valve body upper end and operatively connects to the guillotine. Afirst pressure chamber is defined above and a second pressure chamber isdefined below, the diaphragm.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a left front perspective view of a tractor of the presentdisclosure;

FIG. 2 is a left rear perspective view of a tractor of the presentdisclosure;

FIG. 3 is side view of the tractor;

FIG. 4 is a rear perspective view of the tractor frame showing the seatload adjustment assembly and the seat height adjustment assembly;

FIG. 5 is a rear perspective view similar to that of FIG. 4;

FIG. 6 is a left side perspective view similar to that of FIGS. 4 and 5;

FIG. 7 is a top view of the tractor frame shown in FIG. 6;

FIG. 8A is a right side view of the tractor shown in FIG. 6;

FIG. 8B is a cross-section view through the vehicle gas tank and seat;

FIG. 9 is a lower perspective view of the seat;

FIG. 10 shows a top perspective view of the seat frame;

FIG. 11 shows a rear perspective view of the seat frame of FIG. 10;

FIG. 12 shows a partially fragmented perspective view of the seat in thefully raised position;

FIG. 13 shows the seat of FIG. 12 in the fully lowered position;

FIG. 14 shows an end view looking towards the seat height adjustmentassembly with the locking pawl in the uppermost locking aperture;

FIG. 15 shows a view similar to that of FIG. 14 with the locking pawl inthe middle locking aperture;

FIG. 16 shows a view similar to that of FIG. 14 with the locking pawl inthe lowest locking aperture;

FIG. 17 is a perspective view showing the seat back in the rearward mostposition;

FIG. 18 is a perspective view showing the seat back in the forward mostposition;

FIG. 19 is a perspective view showing the air intake system, and a speedcontrol unit mounted to the throttle valve;

FIG. 20 is a perspective view similar to that of FIG. 19 without theengine and throttle valve in place;

FIG. 21 is a top view of the tractor similar to that shown in FIG. 20;

FIG. 22 is a perspective view of the valve of the speed control unit;

FIG. 23 is a view showing multiple component parts of the speed controlunit;

FIG. 24 is an exploded view of the speed control unit;

FIG. 25A shows the system operations when the speed is less than 25 mph;

FIG. 25B shows the system operations when the speed is greater than 25mph;

DETAILED DESCRIPTION OF THE EMBODIMENT

With reference first to FIGS. 1-3, the tractor is shown generally at 2.The tractor 2 is of the type of a four-wheel drive vehicle having frontdrive wheels 4, and rear drive wheels 6 which support a frame 8 of thetractor. The tractor 2 also includes a seat 10 for a single rider,having a backrest at 12 with a front utility rack 14 and a rear utilityrack 16. The tractor is steerable by way of a steering assembly 18 andis motively projected by way of a drive train at 20 (FIG. 2).

With reference now to FIGS. 4-8, frame 8 is shown in greater detail.Frame 8 is generally comprised of a longitudinally extending upper frameportion 26 which is generally comprised of longitudinally extendingframe members 28 held in a fixed relation by way of a crossbar 30. Alower frame member 32 is rigidly attached to the upper frame member 26by way of frame uprights 34, 36 and 38. The tractor 2 also includes anenhanced rider area which is comprised of a seat height adjustmentassembly shown generally at 40, a seat load adjustment assembly showngenerally at 42 and a backrest fore/aft assembly shown generally at 44(FIG. 3).

With respect to FIGS. 8B and 19, a forward portion of frame 26 is shown,specifically frame members 28. Fuel tank 46 is attached to frame 26, byway of depending legs 48 attached to standoffs 49. Depending legs 48extend rearwardly from standoffs in a cantilevered fashion, as describedfurther herein.

With respect again to FIGS. 4-8, seat load adjustment assembly 42 willbe described in greater detail. Seat load adjustment assembly 42 isgenerally comprised of a load frame 50, a coil spring assembly 52 and aspring retainer 54. With respect to FIGS. 4 and 5, frame 50 is showncomprised of side plate members 56 attached at one end to a rear bracket58 and at the opposite end to a front plate 60. Front plate 60 alsocooperates with the adjustable seat height assembly 40 as will bedescribed herein. Frame 50 also includes a channel 62 which extendsbetween plate 60 and bracket 58. Channel 60 is open on an undersidethereof and includes attachment apertures 64 (FIG. 5) as describedherein. As shown best in FIG. 5, frame 50 includes hinge plates 70 whichare fixed to the bottom of plate members 56, and which flank a bushing72. This allows frame 50 to be pivotally mounted on end tube 74 whichspans between frame members 28. As should be appreciated, this allowsthe entire frame assembly 50 to pivot relative to the frame 8. Finally,and with respect to FIG. 4, front plate 60 includes a plurality ofvertically spaced apertures 80, and an alignment block 82 as furtherdescribed herein.

With respect again to FIGS. 4 and 5, spring retainer 54 includes a rearplate 90 and side plates 92 which terminate in side flanges 94 which inturn are attached to inside surfaces of frame members 28. With referencenow to FIGS. 6 and 7, the mounting of spring 52 will be described ingreater detail. Spring 52 is a compression spring and is shown trappedbetween a rear retainer 100 and a front retainer 102. Rear retainer 100includes an enlarged portion 104, where the enlarged portion 104 has alarger profile than the outside diameter of the coil spring 52, and ispositioned on the inside of spring retainer 54. The retainer 100 alsoincludes an inside diameter portion 106 having a diameter smaller thanthe inside diameter of coil spring 52 to seat within the coil spring 52.Rear retainer 100 would also be attached to a jack screw 110 (see FIGS.5 and 6), which when threaded through nut 112 pushes on rear retainer100, and resultantly increases the compression spring force in coilspring 52.

With respect to FIGS. 7 and 8, upper retainer 102 includes an enlargedportion 110 having a larger profile than the coil spring 52 and areduced diameter section 112 which has a smaller diameter that coilspring 52 and seats inside coil spring 52. It should be appreciated thatenlarged portion 110 would include an anchor (not shown) having anaperture through which a pin may be attached to a rearward one ofapertures 64 (FIGS. 4-5) to attach the top end of coil spring 52 to thecenter channel 62. It should be appreciated then that a downward force F(see FIG. 8) on a front portion of frame 50 allows frame 50 to pivotunder spring force about tube 74 in the direction shown in the arrow asshown in FIG. 8. It should also be appreciated that the compressivespring force in spring 52 is controllable through jackscrew 110.

While spring retainer 54 is fixed, coil spring can pivot about retainer100 during this pivotal movement. However, it also possible to mountspring retainer 54 in a rotatable sense relative to rear tube 120 or tofix spring retainer 50 to rear tube 120 and allow tube 120 to rotaterelative to uprights 34.

With respect now to FIGS. 5 and 6, a dampening assembly is shown tocomprise an upright 122 attached to the crossbar 30, with a channel 124attached to upright 122. A shock or damper 126 is positioned betweenchannel 124 and between apertures 64 in channel 62 (see FIG. 5).

With respect now to FIGS. 9-11, seat 10 will be described in greaterdetail. Seat 10 is comprised of a base portion 130 having a frontsection 132 and a rear section 134, with structural ribs 136 fastenedtherein and extending between the front and rear sections 132, 134. Ribs136 are shown as riveted, but could be fixed by integral molding,adhesives, or other known fasteners. FIG. 9 shows seat 10 with the baseportion 130 with the padding, whereas FIGS. 10 and 11 show only the baseportion 130. Base portion 130 also includes a lower surface 138 havingposts 140 extending therefrom having rubber stops at 142. As shown bestin FIG. 9, seat base 130 is rigidified with steel ribs 144 attached tothe posts 140. As shown in FIG. 9, base front 132 includes two openings146 (only one of which is visible) positioned within molded pockets 148.Finally as shown in FIG. 11, seat frame 130 is equipped with a heightadjustment latch assembly shown at 150.

With respect again to FIG. 4, seat adjusting latch 150 comprises a lever152 having two pin portions 154 extending through a clevis jaw 156 wherethe clevis jaw has an upper portion 158 which flanks a molded portion160 of seat frame 130. Pin portions 154 are fixedly attached to clevisjaws 156, and clevis jaws 156 rotate about an axis through pins 154 uponmovement of handle 152. Clevis jaw 156 also includes a locking pawl 166(FIG. 5) which locks with one of the apertures 80 in front plate 60. Itshould be appreciated that latch assembly 150 includes a torsionalspring 168 such that the clevis jaw 156 is normally biased against theplate 60 with the pawls 166 in a locked condition within the apertures80.

As also best shown in FIG. 4, seat frame 130 includes a recess 170 whichaligns with and receives alignment block 82 to allow the seat to pivotupwardly and downwardly, but prevents movement of the seat frame 130 ina lateral sense. As shown best in FIG. 4, rubber stops 142 are alignedwith frame members 28 to prevent hard engagement of the seat frame 130with the frame members 28 in a jounce situation. Seat 10 is held inposition with depending legs 48 positioned in openings 146 (see FIG.8B), by block portion 82 positioned in opening 170 (see FIG. 4), andwith latch assemblies 150 positioned within apertures 80 of plate 60.

As shown in FIGS. 12 and 13, the seat 10 may move through extremepositions A and B as measured from the utility rack 16. FIGS. 14-16 alsoshow the seat position with the locking pawls 166 in the variousapertures 80. As shown between the comparison of FIGS. 12 and 13, theseat has a vertical movement of 42.926 mm/1.69″.

With respect to FIGS. 3 and 17, the seatback adjustment assembly 44 iscomprised of tubular frame member 180 attached to seat back padding 182,and locking channels 190 fixedly attached to rear rack 16. Frame portion180 also includes a horizontally extending portion 188 positioned withinlocking channels 190 which are locked by way of a threaded thumb wheel192. It should be appreciated that when the thumb wheels 192 areloosened and retracted, the horizontal tube portions 188 may moveforwardly and backwardly within the channels 190 to allow the user toposition the seatback in a number of various locations, and can lock theseatback to any position between extreme positions. FIGS. 17 and 18 showthose extreme positions, where the difference between positions C and Dallows 60 mm of travel for the seat back.

As designed the tractor 2 meets all of the directives as mentionedabove. The seat back moves forwards and backwards as disclosed in FIGS.17-18. The seat also meets the seat load characteristics by providingthe pivotal suspension frame 50 with the spring 52 loaded upon a forceon the seat. The spring rate of the spring as disclosed is 170 lb_(f)per inch of compression, which allows an approximate load variance forthe embodiment shown, of between 155 N and 1200 N and. The heightvariance is accomplished by interconnection of the end of the seat tothe front end of the suspension frame 50.

With reference now to FIGS. 19-25, a speed control device for thetractor will be described. With reference first to FIG. 19, the tractor2 is shown having an air intake system shown generally at 200 comprisingan airbox 202, an air intake snorkel 204 connected to the airbox 202, aspeed control unit 206 connected intermediate the airbox 202 and athrottle valve 208. It should be appreciated that the throttle valve isattached to the air intake of the engine of the tractor in a knownmanner.

With reference to FIG. 22, speed control unit 206 generally includes aspeed control body shown generally at 210 with an intake side 212connected to the airbox 202 and an exhaust side 214 connected to thethrottle body 208. The speed control unit further includes a guillotinestyle gate 216 and a top cap 218 having an air input nipple 220. Withreference now to FIGS. 23 and 24, the speed control unit is shown in anexploded manner and, in addition, shows an inner housing insert 222.

As shown in FIG. 24, speed control body 210 includes a central bodyportion 224 which fluidly communicates with an open upper area 226 whichis surrounded by a flange 228. Insert 222 is receivable into the centralbody portion 224 and into the position as shown in FIG. 22. Insert 222together with housing 210 define an air channel 230 between intake side212 and exhaust side 214. As best shown in FIG. 22, control body 210includes a raised section or “tonsil” shown at 230. The raised section230 is only on one side (the intake side 212) and only extends up to theguillotine gate member 216 as described further herein. Insert 222 isfixedly receivable within central body portion 224 by way of a pair offasteners 236. As best shown in FIG. 23, insert 222 includes an innerprofile 238 having an H-shaped channel as described further herein.

Meanwhile diaphragm assembly 216 includes a guillotine gate valve member240 attached to a diaphragm 242 where the guillotine valve member 240has an H-shaped configuration cooperable with opening 238 and isreceivable therein and movable upwardly and downwardly transversely ofthe opening 230. It should also be appreciated that the diaphragm 242seats on top of opening 226 of the body 210 and that the guillotinevalve member 240 is movable upwardly and downwardly within the insert222 based upon the position of the center of the diaphragm.

The cap 218 is fastened to the top of the body 210 by way of fasteners243 which are received through apertures of cap 218 and are received inapertures 244 of body 210. This forms a sealed condition around theperiphery of opening 226 by way of the diaphragm. A spring 250 and cap252 are positioned between diaphragm 242 and cap 218 such that theguillotine valve member 240 is normally spring-loaded to a positionwhere the guillotine forms a closed condition within the opening. Asalso shown in FIG. 23, diaphragm member 216 includes a bleed hole 260which extends through the guillotine 240 and upwardly through thediaphragm 242 as further described herein. A first pressure chamber isdefined under the cap 218 and above the diaphragm, and a second pressurechamber is defined beneath the diaphragm.

Raised section 230 allows for minimal air turbulence entering thethrottle. Due to the flat bottom shape of the guillotine valve member240, the valve member provides a clean conformance with the raisedsection, to close off the air flow when the guillotine valve member 240is fully down. There is a certain amount of air leakage that goesthrough and there is the defined leakage through orifice 260, whichpreferably is a 1.27 mm hole. This orifice provides the defined leakageas well as a damping effect to the guillotine valve member movement inthe up and down direction.

With reference now to FIGS. 25A and 25B, the operation of speed controldevice 206 will be described in greater detail. First with respect tocontrolling the speed, it should be appreciated that any particularspeed limit may be set as an upper range but in this particular example,the speed is set to control at a top end speed of 25 mph.

As shown in FIG. 25A, a speed pickup is shown diagrammatically at 270and this speed pickup could take many different configurations. However,for example, in this embodiment the speed pickup is a Hall Effect sensorlocated adjacent to the rear wheels which pick up signals from the wheelspeed and delivers that information to an engine control unit 272. Theengine control unit 272 is also in communication with a solenoid valve274 which in turn is connected to nipple 220 by a hose 276. Vehiclespeed is fed to the engine control unit 272. Solenoid 274 and hose 276can allow atmospheric pressure into the top of the speed control unit206, and to the topside of diaphragm 242 when opened.

In the embodiment of FIG. 25A, the tractor is assumed to be operating ata speed of less than 25 mph. This information is fed to engine controlunit 272, which closes solenoid valve 274. When the operator tries toincrease speed, the engine will create a vacuum pressure P1 on theengine side of speed control unit 206. The pressure on the opposite sideof speed control unit 206 P2 (FIG. 25A) is greater, and therefore thegreater pressure P2 act on the bottom side of the diaphragm 242 andraises it upwardly. Air on the topside of the diaphragm 242 is allowedto bleed through bleed hole 260 (FIG. 23).

If the tractor comes to a speed of 25 mph or greater, and as shown inFIG. 25B, the speed pick up 270 senses that condition and sends amessage to engine control unit 272 that the operational speed is greaterthan 25 mph. The engine control unit 272 then sends a signal to solenoidvalve 274 which allows atmospheric air through hose 276 and allowsatmospheric pressure through nipple 220. This places a force on thebackside of diaphragm 242 in the direction of the arrow shown in FIG.25B. This closes the diaphragm and moves the guillotine valve member 240to its most restrictive position and therefore starves the engine ofair.

This condition makes the engine control unit believe that it is at adifferent operating condition (for example, a higher altitude condition)and therefore, also adjusts such other operating conditions such as fuelinput. The net result of the speed control unit 206 is the vehicle speedis reduced to a speed at or below 25 mph. The bleed hole 260 allowssmooth acceleration and deceleration without jerky motion.

While this invention has been described as having an exemplary design,the present invention may be further modified within the spirit andscope of this disclosure. The application is, therefore, intended tocover any variations, uses, or adaptations of the invention using itsgeneral principles. Further, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this invention pertains.

What is claimed is:
 1. A vehicle, comprising: a frame; ground engagingelements; an engine for motively driving one or more of the groundengaging elements; and an air valve positioned intermediate an airintake and the engine wherein the air valve is comprised of: a valvebody having an upper end, and a lower end having an intake side and anexhaust side, wherein an air channel opening extends between the intakeside and the exhaust side; a gate valve member positioned within thevalve body and operated by a guillotine movable transversely of the airchannel opening between up and down positions, the gate valve memberproviding an opened and closed condition between the intake side and anexhaust side, the gate valve member closing off air flow when theguillotine is in the down position; a diaphragm positioned at the valvebody upper end and operatively connected to the guillotine, theguillotine being movable based upon the position of a center of thediaphragm, a first pressure chamber being defined above and a secondpressure chamber being defined below, the diaphragm; and an aperturethrough the diaphragm connecting the first and second pressure chamber.2. The vehicle of claim 1, wherein the aperture extends down through thegate valve member.
 3. The vehicle of claim 1, further comprising acontroller assembly for opening and closing the air valve, the assemblyincluding a speed sensing mechanism and a controlling unit for openingand closing the air valve.
 4. A vehicle comprising: a frame; groundengaging elements; an engine for motively driving one or more of theground engaging elements; and an air valve positioned intermediate anair intake and the engine wherein the air valve is comprised of: a valvebody having an upper end, and a lower end having an intake side and anexhaust side; a gate valve member positioned within the valve body andoperated by a guillotine, the gate valve member providing an opened andclosed condition between the intake side and an exhaust side; adiaphragm positioned at the valve body upper end and operativelyconnected to the guillotine, a first pressure chamber being definedabove and a second pressure chamber being defined below, the diaphragm;an aperture through the diaphragm connecting the first and secondpressure chamber; and a controller assembly for opening and closing theair valve, the assembly including a speed sensing mechanism and acontrolling unit for opening and closing the air valve; wherein thecontrolling unit, when the vehicle is operating at a speed below anupper speed limit, allows the diaphragm to be raised and maintains theguillotine and the gate valve open.
 5. The vehicle of claim 4, whereinthe controlling unit, which when the vehicle operates at a speedapproaching the upper speed limit, controls the diaphragm to a closedposition, which closes the air valve and slows the vehicle.
 6. Thevehicle of claim 4, wherein the controlling unit is a solenoid valve. 7.The vehicle of claim 6, wherein the solenoid valve is connected to anarea above the diaphragm.
 8. The vehicle of claim 7, wherein when thevehicle is operating at a speed below an upper speed limit, the solenoidvalve is closed.
 9. The vehicle of claim 8, wherein when the vehicle isoperating at a speed below an upper speed limit, the solenoid valve isopen and connects atmospheric pressure to the area above the diaphragm,and closes the guillotine.
 10. A vehicle, comprising: a frame; groundengaging elements; an engine for motively driving one or more of theground engaging elements; and an air valve positioned intermediate anair intake and the engine wherein the air valve is comprised of: a valvebody having an upper end, and a lower end having an intake side and anexhaust side, the intake side comprising a raised and contoured section;a gate valve member positioned within the valve body and operated by aguillotine, the gate valve member providing opened and closed positions,wherein in the closed position, the gate valve member is positionedbehind the raised and contoured section; and a diaphragm positioned atthe valve body upper end and operatively connected to the guillotine, afirst pressure chamber being defined above and a second pressure chamberbeing defined below, the diaphragm.
 11. The vehicle of claim 10, whereinthe raised and contoured section extends upwardly from front to back,and from the side to side towards a center of the valve body.
 12. Thevehicle of claim 10, wherein an aperture extends through the diaphragmconnecting the first and second pressure chamber.
 13. The vehicle ofclaim 12, wherein the aperture ends down through the gate valve member.14. The vehicle of claim 10, further comprising a controller assemblyfor opening and closing the air valve, the assembly including a speedsensing mechanism and a controlling unit for opening and closing the airvalve.
 15. The vehicle of claim 14, wherein the controlling unit, whenthe vehicle is operating at a speed below an upper speed limit, allowsthe diaphragm to be raised and maintains the guillotine and the gatevalve open.
 16. The vehicle of claim 14, wherein the controlling unit,which when the vehicle operates at a speed approaching the upper speedlimit, controls the diaphragm to a closed position, which closes the airvalve and slows the vehicle.
 17. The vehicle of claim 14, wherein thecontrolling unit is a solenoid valve.
 18. The vehicle of claim 17,wherein the solenoid valve is connected to an area above the diaphragm.19. The vehicle of claim 17, wherein when the vehicle is operating at aspeed below an upper speed limit, the solenoid valve is closed.
 20. Thevehicle of claim 19, wherein when the vehicle is operating at a speedbelow an upper speed limit, the solenoid valve is open and connectsatmospheric pressure to the area above the diaphragm, and closes theguillotine.